MIDTERM LEC: CLEARING

Question 1

Removing dehydrant from tissue, and replacing it with a fluid miscible to both dehydrant and embedding agent

Answer 1

CLEARING

Question 2

Makes tissues “transluscent” or transparent, hence the term clearing

Answer 2

CLEARING

Question 3

Most are flammable fluids and have low boiling points

Answer 3

CLEARING

Question 4

Excessive clearing may cause brittleness

Answer 4

CLEARING

Question 5

Characteristics of a Clearing Agent:

Answer 5

 Miscible with alcohol, paraffin, and mounting media
 Causes minimum shrinkage
 Should not dissolve Aniline dyes
 Should not evaporate quickly in water bath
 Makes tissues transparent

Question 6

CLEARING SOLUTIONS:

Answer 6

1. Xylene/Xylol
2. Benzene
3. Toluene
4. Chloroform
5. Cedarwood Oil
6. Aniline Oil
7. Clove Oil
8. Carbon tetrachloride
9. Tetrachloride
10. Methyl benzoate and Methyl salicylate

Question 7

15-30 mins to 1hr working time (most rapid)

Answer 7

Xylene/Xylol

Question 7

Most commonly used clearing agent

Answer 7

Xylene/Xylol

Question 8

Colorless

Answer 8

Xylene/Xylol

Question 8

Becomes milky when tissues are not completely dehydrated

Answer 8

Xylene/Xylol

Question 9

Not for nervous tissues and lymph nodes because will cause hardening and shrinkage

Answer 9

Xylene/Xylol

Question 10

Urgent biopsies and routine purposes (15 to 60 mins); very volatile in paraffin oven

Answer 10

Benzene

Question 11

Damages the bone marrow leading to aplastic anemia

Answer 11

Benzene

Question 11

Substitute for xylene or benzene, but slower (1-2hrs)

Answer 11

Toluene

Question 12

Toxic upon prolonged exposure when used in high conc

Answer 12

Toluene

Question 13

Does not cause brittleness even when tissues are left for 1 day; not carcinogenic

Answer 13

Toluene

Question 14

For tissue blocks up to 1cm thick; recommended for large & tough tissues; CNS tissues, lymph nodes, and embryos

Answer 14

Chloroform

Question 15

Does not make tissues translucent

Answer 15

Chloroform

Question 16

Toxic to liver, tissues tend to float

Answer 16

Chloroform

Question 17

For CNS tissues and cytology, smooth muscle, skin

Answer 17

Cedarwood oil

Question 18

Becomes milky in prolonged storage

Answer 18

Cedarwood oil

Question 19

Forms crystals with acetic-alcohol fixed tses
(remedy: heat to 200OC prior to using)

Answer 19

Cedarwood oil

Question 20

For skin and smooth muscle, but tends to be adulterated

Answer 20

Clove Oil

Question 20

P: for insects, embryos, and delicate tses

Answer 20

Aniline Oil

Question 21

Properties and disadvantages are similar to
chloroform but is relatively cheaper

Answer 21

Carbon tetrachloride

Question 22

o For double embedding
o Slow acting

Answer 22

Methyl benzoate and Methyl salicylate

Question 22

Shortened turnaround time

Answer 22

Tetrahydrofuran

Question 23

OTHER CLEARING SOLUTION:

Answer 23

1. Gum Syrup & Glycerin
2. Oil of Bergamot
3. Oil of Origanum
4. Oil of wintergreen
5. Carbon Disulfide
6. Carbol Xylene
7. Terpineol
8. Phenol
9. High Test Aviation Lead-free gasoline

Question 24

for skin and smooth muscle

Answer 24

Oil of Bergamot

Question 24

used when clearing directly from
water (as in a frozen section)

Answer 24

Gum Syrup & Glycerin

Question 25

for skin

Answer 25

Oil of Origanum

Question 26

artificial oil, for delicate tissues

Answer 26

Oil of wintergreen

Question 27

for smooth muscle; has foul odor

Answer 27

Carbon Disulfide

Question 28

for friable tissues

Answer 28

Carbol Xylene

Question 29

for delicate tissues like eyes

Answer 29

Terpineol

Question 30

for smooth muscles

Answer 30

Phenol

Question 31

excellent clearing agent

Answer 31

High Test Aviation Lead-free gasoline